Bolas's Ultimatum

Ultimatium (Whenever you cast this spell,
choose an opponent. That opponent chooses Salvation or Damnation. This spell has the chosen mode's text.)
----Salvation: Target player separates all
permanents they control into two piles. You
choose one pile. Gain control of all permanents in
the chosen pile.
----Damnation: Destroy all permanents target
player controls.
Join, or die.